The present invention relates to a pellicle used for manufacturing a semiconductor such as LSI, super LSI or the like or a liquid crystal display, and in particular, suitable for an exposure method in which light having a wavelength of substantially 220 nm is used.
In manufacturing a semiconductor such as LSI, super LSI or the like, or a liquid crystal display device, there has conventionally been conducted patterning by irradiating light having a wavelength of 240 nm or more to a semiconductor wafer or a liquid crystal display substrate through an original sheet to be exposed to light, e.g., a mask or a reticle (herein-below, referred simply to as an original sheet). In this case, if dust deposits on the surface of the original sheet on which the patterning is conducted, the dust will absorb, reflect or deflect light for exposure, whereby the dimensional accuracy and the quality are reduced and the outer appearance becomes poor. Therefore, working for exposing light has to be conducted in a clean room.
However, it is difficult to keep the original sheet clean.
For the purpose of preventing the deposition of dust on the original sheet, the work for exposing light is generally conducted by using a pellicle. FIG. 4 is a perspective view showing a conventional pellicle attached to an original sheet, and FIG. 5 is a cross-sectional view taken along a line Axe2x80x94A in FIG. 4. A pellicle 1 comprises a pellicle frame 5 and a pellicle membrane 2 for transmitting exposure light, which is bonded to an opening portion of the pellicle frame 5 by an adhesive 4. When working for exposing light is to be conducted, the pellicle 1 is attached to the original sheet 7 by bonding the pellicle frame 5 to it by an adhesive 6. The original sheet 7 attached with the pellicle 1 can be used semi-permanently unless the pellicle membrane 2 or the pellicle frame 5 is broken, because there is no possibility of a reduction of light transmittance or invasion of dust.
On the other hand, the wavelength of light for exposure used for manufacturing a semiconductor such as LSI, super LSI or the like has more and more been shortened according to a demand of minimizing the size, and at present, a technique of exposing light having a wavelength of 220 nm or less from an F2 laser, is proposed. The original sheet used for such exposure may cause a reduction in transmittance of light by the deposition of an organic type gas existing in a clean room at the time of exposing light. Further, the original sheet is housed in a casing made of synthetic resin such as polyacrylate, polystyrene, polypropylene, polyethylene, polycarbonate, ABS resin or the like for the purpose of storage and transporting. It has been found that such casing generates an organic type gas, and the generated gas deposits on a surface of the housed original sheet to reduce its transmittance of light.
Therefore, in general, cleaning is conducted to the original sheet before the exposure to light. The inventors of this application proposed a technique of removing, as a cleaning method, in which ultra-violet rays such as F2 laser or an Xe2* excimer lamp (herein-below, referred to as xe2x80x9ccleaning lightxe2x80x9d) is irradiated to thereby decompose organic matters (PCT/JP00/01869). The pellicle membrane is, therefore, required to have a sufficient durability (light-resistance) to such cleaning light. Further, the adhesive 4 is also required to have light-resistance as well because the cleaning light is irradiated to the adhesive 4 for bonding the pellicle membrane 2 to the pellicle frame 5. In conventional technique, a polybutene resin, an acrylic resin, an epoxy resin type adhesive, a silicone type adhesive or the like is used as the adhesive 4. However, any adhesive material is not always sufficient in terms of light-resistance, and the bonding strength decreases with an increase of the number of times of irradiation of the cleaning light. As a result, there create problems that the pellicle membrane peels off from the pellicle frame to produce a gap whereby dust-proof ability becomes insufficient, and a deteriorated portion of the adhesive becomes dust, which deposits on the pattern-written surface of the original sheet 7 as dust.
The present invention has been achieved in view of the above-mentioned problems, and is to provide a pellicle capable of preventing the deterioration of an adhesive for bonding the pellicle membrane to the pellicle frame, due to exposure to cleaning light.
According to the present invention, there is provided a pellicle comprising a pellicle frame and a pellicle membrane composed of synthesized silica glass bonded to an opening of the pellicle frame by an adhesive, wherein a light shielding member for shielding ultra-violet rays irradiated to the adhesive is provided.
In the above-mentioned pellicle, it is preferable that the light shielding member is composed of a metal or a metal oxide. Further, it is preferable that the light shielding member is a membrane or a sheet having a thickness of 50 nm or more.